Ag nanoparticles supported on a magnetic NiFe2O4/MIL-101(Fe) metal–organic framework nanocomposite for the room temperature rapid catalytic reduction of nitrophenols and nitroanilines

Abstract

In the present research, a novel Ag@NiFe₂O₄/MIL101(Fe) ternary magnetic nanocomposite was synthesized through a hydrothermal pathway for the room temperature catalytic reduction of nitrophenols and nitroanilines. Structural, optical, and magnetic properties of the nanocomposite were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible (UV-vis) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS), vibrating sample magnetometry (VSM), Raman spectroscopy and BET surface analysis. The catalytic reduction of nitrophenols and nitroanilines was studied at room temperature to investigate the catalytic activity of the Ag@NiFe₂O₄/MIL101(Fe) nanocomposite. The results showed that the reduction of 4-nitrophenol (0.2 mM) in the presence of Ag(25 wt%)@NiFe₂O₄/MIL101(Fe) and NaBH₄ (20 mM) as a green reducing agent was completed within 3 min, and the Ag@NiFe₂O₄/MIL101(Fe) ternary nanocomposite has a very effective performance in the conversion of these contaminants. In addition, the relatively high specific surface area of MIL-101(Fe), the magnetic properties of NiFe₂O₄ and the effect of silver nanoparticles increase the synergy and increase the removal efficiency of nitroaromatic pollutants. The fabricated composite containing 25 wt% of Ag demonstrated superior catalytic performance over other composites. The ternary magnetic catalyst can be easily separated from the reaction medium using an external magnetic field. The recycled nanocatalyst was used again after separation and washing. After 5 uses, the synthesized nanocomposite maintained its efficiency as a catalyst in reducing nitro-aromatic compounds by 100%, which shows the high stability of the catalyst.